The invention herein relates generally to a fluid control device, and more particularly, to a device for rapid and accurate control of a fluid that is under pressure. The fluid to be controlled can be various gases or liquids.
It is known to use a piezoelectric element as a valve driver. Cummins, U.S. Pat. No. 4,340,083 discloses a valve including a piezoelectric bar arranged in the valve reservoir and mounted as a cantilevered beam with the free end of the piezoelectric bar being mounted for movement toward and away from a valve seat surrounding a control opening in response to the application of an electrical signal.
It is known to use a stack of piezoelectric discs as a driver for an undamped spring-mass system. Smiley, U.S. Pat. No. 3,614,486 discloses the use of a stack of thin piezoelectric discs as a driver for applications which require high speed, accuracy and virtually no vibration.
The known devices position the piezoelectric member in contact with the fluid. Thus, the known devices require protective coatings on the piezoelectric beam and electrical connections to protect the same from chemical attack by the fluid. Additionally, mechanical problems result from the fluid contact with the piezoelectric member.
The invention provides a fluid control device or valve including a piezoelectric transducer that functions to control the flow of the fluid. The invention herein differs from prior valves by providing the piezoelectric transducer outside the valve reservoir whereby the piezoelectric transducer does not contact the fluid and by providing a structure that is simple, economical to manufacture and highly effective for the intended purpose of rapidly and accurately controlling fluid flow.